Parasites as biological tags for stock discrimination of the Brazilian flathead Percophis brasiliensis in the south‐west Atlantic

Abstract

Three stocks of the Brazilian flathead Percophis brasiliensis were identified on the coast of Argentina and Uruguay using parasites as biological tags. A total of 177 fish were examined and 23 parasite species were found. Fish were caught in four zones: north of the Argentine–Uruguayan Common Fishing Zone (34°30′–36°30′ S; 53°30′–56°00′ W), south of the Argentine–Uruguayan Common Fishing Zone (38°08′ S 57°32′ W), El Rincón zone (39–41° S; 60–62° W) and San Matías Gulf (41°40′–42°10′ S; 63°50′–65°00′ W). Discriminant analyses allowed the identification of three discrete stocks in the four zones (86·44% of classified samples were correctly identified), with P. brasiliensis from both north and south of the Argentine–Uruguayan Common Fishing Zone clumping together, as a single stock. Some species were important in discriminating among groups, Anisakis simplex was related to southern areas, while Grillotia sp., Corynosoma australe and Hysterothylacium sp. were important in determining the position of fish from the Argentine–Uruguayan Common Fishing Zone. These results were corroborated by comparing parasite prevalence and abundance among zones. The main differences were observed in those comparisons involving fish from the San Matías Gulf. Fish from the Argentine–Uruguayan Common Fishing Zone were characterized by higher infections of Grillotia sp., C. australe, Corynosoma cetaceum and Hysterothylacium sp., while the samples from El Rincón and San Matías Gulf showed higher infections of A. simplex. Samples from San Matías Gulf were characterized by lower levels of parasitism for all other species. Differences in environmental factors and their influence on the distribution of zooplankton and other hosts in the food web may be differentially shaping the parasite community structure in each zone, resulting in identifiable stocks of the P. brasiliensis. The present study confirmed the existence of regional biological tags that delineated fish assemblages.

Use of otolith strontium:calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

“…The simultaneous use of the otolith Sr:Ca and Zn:Ca ratios did not allow us to differentiate populations from ER and SMG, but it allowed us to discriminate them from the population located in AUCFZ. Even though this result does not completely agree with those reported by Braicovich & Timi (2008), it further supports the occurrence of different fish stocks. These populations may be divided, at least in part, by marine fronts.…”

“…The occurrence of three different stocks of P. brasiliensis in the southwestern Atlantic Ocean has already been suggested by Braicovich & Timi (2008), based on the analysis of parasite composition. According to these authors the stocks were located in AUCFZ, ER and SMG, respectively.…”

“…However, sustainable fishery management practices have never been implemented, due to the scarce information available for the identification of P. brasiliensis stocks. On this regard, Braicovich & Timi (2008) have suggested the occurrence of three fish stocks in the Argentine-Uruguayan Common Fishing Zone (AUCFZ), El Rincón (ER) and San Matías Gulf (SMG) (Fig. 1), based on the study of parasites.…”

Digenetic trematodes of the Brazilian flathead, Percophis brasiliensis Quoy et Gaimard, 1825 (Percophidae, Perciformes), from Argentinean and Uruguayan waters

“…In the present paper the list of digenean species parasitizing P. brasiliensis is increased from 6 to 9, including the identification at the specific level of worms previously reported by Braicovich and Timi (2008) as Ectenurus sp. and Lecithocladium sp.…”

“…The material studied was deposited in the Helminthological Collection of the Museo de la Plata (CHMLP), La Plata, Argentina. Prevalence and mean intensity of infection were calculated according Bush et al (1997) for the whole sample, including 177 flatheads previously examined by Braicovich and Timi (2008). Bray (1990a), mainly by the presence of a long sinus-sac reaching the middle region of the ventral sucker.…”